Amplifying Processing of Livestock in the United States Act or the A–PLUS ActThis bill directs the Department of Agriculture&nbsp;(USDA) to revise its regulations to allow certain packers to hold an ownership interest in, finance, or participate in the management or operation of a market agency selling livestock on a commission basis.The bill applies to packers that have a cumulative slaughter capacity of (1) less than 2,000 animals per day or 700,000 animals per year with respect to cattle or sheep, and (2) less than 10,000 animals per day or 3 million animals per year with respect to hogs.In addition,&nbsp;USDA must revise its regulations to&nbsp;include a disclosure requirement for a market agency that has an ownership interest in, finances, or participates in the management or operation of a packer. Specifically, the market agency must disclose the existence of such ownership interest, financial relationship, or participation.